Copernicus Downstream Service Supports Nature-Based Flood Defense: Use of Sentinel Earth Observation Satellites for Coastal Needs

This is a copy of the article published in Sea-Technology Magazine, which the authors have bought the rights to redistribute.With an uncertain future that includes climate change, sea level rise and increasing coastal populations, being able to make informed policy decisions in coastal zones will be critical for ensuring the well-being of citizens, the environment and the sustainability of economic activities. Earth observation (EO) can be used to efficiently and systematically provide the key information needed to make these decisions. However, getting access to the right EO in- formation can be a complicated and costly business, limiting availability. However, the launch in April 2014 of the first Sentinel satellite from Europe’s flagship EO program, Copernicus, represents a major advance in the availability of EO data, which has great potential to benefit numerous sectors involved in marine and coastal activities. We discuss some examples of applications being developed and give an example of a new service which intends to support nature-based flood defense schemes.The research leading to these results has received funding from the European Union Seventh Framework Program (FP7/2007-2013) under grant agreement n° 607131. All views presented are those of the authors. The EU is not liable for any use that may be made of the information contained herein.PDF, 5 pages, 20.4 M

The Role of Mean Sea Level Annual Cycle on Extreme Water Levels Along European Coastline

The knowledge of extreme total water levels (ETWLs) and the derived impact, coastal flooding and erosion, is crucial to face the present and future challenges exacerbated in European densely populated coastal areas. Based on 24 years (1993-2016) of multimission radar altimetry, this paper investigates the contribution of each water level component: tide, surge and annual cycle of monthly mean sea level (MMSL) to the ETWLs. It focuses on the contribution of the annual variation of MMSL in the coastal flooding extreme events registered in a European database. In microtidal areas (Black, Baltic and Mediterranean Sea), the MMSL contribution is mostly larger than tide, and it can be at the same order of magnitude of the surge. In meso and macrotidal areas, the MMSL contribution is 30%) in the North Sea. No correlation was observed between the average annual cycle of monthly mean sea level (AMMSL) and coastal flooding extreme events (CFEEs) along the European coastal line. Positive correlations of the component variance of MMSL with the relative frequency of CFEEs extend to the Central Mediterranean (r = 0.59), North Sea (r = 0.60) and Baltic Sea (r = 0.75). In the case of positive MMSL anomalies, the correlation expands to the Bay of Biscay and northern North Atlantic (at >90% of statistical significance). The understanding of the spatial and temporal patterns of a combination of all the components of the ETWLs shall improve the preparedness and coastal adaptation measures to reduce the impact of coastal flooding

Heavy Guadalquivir River discharge detection with satellite altimetry: The case of the eastern continental shelf of the Gulf of Cadiz (Iberian Peninsula)

© 2015 COSPAR. Published by Elsevier Ltd. All rights reserved. In situ water levels in the Guadalquivir River estuary mouth show the effect of strong river freshwater discharges on the monthly means of the sea level on a yearly basis. Accurate altimeter products oriented toward coastal zones are increasing the number of potential applications at different spatiotemporal scales. The present work is focused on the analysis of the sea-level variability in the eastern shelf of the Gulf of Cadiz (between North Africa and the southwestern side of the Iberian Peninsula), adjacent to the Guadalquivir River estuary. Sixteen years (1994-2009) of along-track and standard AVISO maps of sea-level anomalies (SLAs) have been used to generate a new high-resolution product with increased spatiotemporal resolution. The use of a bathymetry constraint and smaller correlation scales in the methodology developed to generate high-resolution altimeter products improves the characterization of the mesoscale signals in the coastal strip adjacent to the estuary due to strong river freshwater discharges. This has been confirmed by the analysis of along-track SLA data in the vicinity of the estuary. The daily evolution (2 weeks) of the sea level obtained in the event of December 2009 might be related to the river plume extension observed by optical Moderate Resolution Imaging Spectrometer (MODIS) images. The spatiotemporal distribution of the altimeter tracks available in the study area might compromise the mapping capabilities to capture coastal and fine-scale features.This work has been partially supported by the ALCOVA Project (CTM2012-37839) funded by the Spanish Ministerio de Economía y Competitividad and FEDERPeer Reviewe

Delimitation of Urban Areas with Waterfront: an Application of the Theory of Socio-Ecological Coastal Systems

La delimitación de áreas de estudio es un principio básico para la gestión ambiental, especialmente para la Gestión Integrada de Áreas Litorales, así como para planes de urbanismo. La determinación geográfica de ciudades costeras desde un enfoque socio-ecológico, permite la implementación de la Gestión Basada en Ecosistemas y un manejo más integrado, sostenible y resiliente, que fomente la biodiversidad urbana y la preservación de ecosistemas naturales. Sin embargo, la planificación y gestión de áreas litorales se ha enfocado históricamente a áreas regionales y no ha fomentado un estudio más localizado de espacios urbanos en el Borde Costero. Por lo tanto, esta investigación se centra en la delimitación del Borde Costero Urbano y su relación con las Tierras Litorales según la teoría de los Sistemas Costeros Socio-Ecológicos. Además, el uso de técnicas de teledetección permite el monitoreo de la expansión urbana y la pérdida de vegetación alrededor de los anillos urbanos. El estudio se desarrolla en cuatro ciudades del litoral de la provincia de Cádiz (España): Sanlúcar de Barrameda, Cádiz, Conil de la Frontera y Algeciras. Según los resultados de esta investigación, la delimitación del Borde Costero Urbano es un paso fundamental para el monitoreo efectivo de los ecosistemas urbanos y costeros, la implementación de la Gestión Basada en Ecosistemas y la Gestión Integrada de Áreas Litorales.The delimitation of study areas is a basic principle for environmental management, especially for the Integrated Coastal Zone Management as well as for urban planning. The geographic determination of coastal cities allows the implementation of Ecosystem-Based Management and a more comprehensive, sustainable, and resilient approach that promotes urban biodiversity and the preservation of natural ecosystems. However, the theory and management of coastal areas has historically focused on regional areas and has not fostered a more localized study of urban spaces in the Shoreland. Therefore, this research focuses on the delimitation of the Urban Shoreland and its relationship with the Coastal Uplands according to the theory of Socio-Ecological Coastal Systems. Additionally, this research used remote sensing techniques for the monitoring of urban expansion and loss of vegetation around the urban ring in the cities of Cádiz, Algeciras, Sanlúcar de Barrameda and Conil de la Frontera in the province of Cádiz, Spain. According to the results of this research, the delimitation of the Urban Shoreland is a fundamental step for the effective monitoring of urban and coastal ecosystems, the implementation of Ecosystem-Based Management and the Integrated Coastal Zone Management

The Use of Sentinel-3 Altimetry Data to Assess Wind Speed from the Weather Research and Forecasting (WRF) Model: Application over the Gulf of Cadiz

This work presents the quality performance and the capabilities of altimetry derived wind speed (WS) retrievals from the altimeters on-board Copernicus satellites Sentinel-3A/B (S3A/B) for the spatial assessment of WS outputs from the weather research and forecasting (WRF) model over the complex area of the Gulf of Cádiz (GoC), Spain. In order to assess the applicability of the altimetry data for this purpose, comparisons between three different WS data sources over the area were evaluated: in situ measurements, S3A/B 20 Hz altimetry data, and WRF model outputs. Sentinel- 3A/B WS data were compared against two different moored buoys to guarantee the quality of the data over the GoC, resulting in satisfying scores (average results: RMSE = 1.21 m/s, r = 0.93 for S3A and RMSE = 1.36 m/s, r = 0.89 for S3B). Second, the WRF model was validated with in situ data from four different stations to ensure the correct performance over the area. Finally, the spatial variability of the WS derived from the WRF model was compared with the along-track altimetry-derived WS. The analysis was carried out under different wind synoptic conditions. Qualitative and quantitative results (average RMSE < 1.0 m/s) show agreement between both data sets under low/high wind regimes, proving that the spatial coverage of satellite altimetry enables the spatial assessment of high-resolution numerical weather prediction models in complex water-covered zones

Wind-induced cross-strait sea level variability in the Strait of Gibraltar from coastal altimetry and in-situ measurements

Coastal altimetry products are available and are being extensively validated. Their accuracy has been assessed in many coastal zones around the world and they are ready for exploitation near the shore. This opens a variety of applications of the sea level data obtained from the specific reprocessing of radar altimeter signals in the coastal strip. In this work, we retracked altimeter waveforms of the European Space Agency satellites: ERS-2 RA and Envisat RA-2 from descending track (#0360) over the eastern side of the Strait of Gibraltar using the Adaptive Leading Edge Sub-waveform (ALES) retracker. We estimated along-track Sea Level Anomaly (AT_SLA) profiles (RA-2) at high posting rate (18 Hz) using improved range and geophysical corrections. Tides were removed with a global model (DTU10) that displays a good performance in the study area: the mean root square sum (RSS) of the main constituents obtained with DTU10 and 11 tide gauge stations was 4.3 cm in agreement with the RSS using a high-resolution local hydrodynamic model (UCA2.5D) (4.2 cm). We also estimated a local mean sea surface by reprocessing ERS-2/Envisat waveforms (track #0360) with ALES.This work was partially funded by the European Union's Interreg V-A España – Portugal (POCTEP) 2014-2020 project: OCASO under grant agreement: GA 0223_OCASO_5_E

Internal waves in the Strait of Gibraltar and their role in the vertical mixing processes within the Bay of Algeciras

This article presents some of the results of an oceanographic survey carried out in the Bay of Algeciras (Strait of Gibraltar) as part of a research project intended to assess the environmental quality of the Bay. One of the most interesting findings was the step-like patterns presented by density profiles within the Bay, which were indicative of notable vertical mixing activity there. The analysis of the observations indicates that those mixing processes may be explained by the interaction between the local internal tide dynamics and the large amplitude internal waves entering the Bay, which seem to originate from the Camarinal Sill region

Foreshore Assessment using Space Technology

Poster presented in SENTINEL-2 for Science Workshop (ESA-ESRIN, Frascati, Italy) on the 20th, 21st and 22nd May 2014. See more information about this workshop in http://seom.esa.int/S2forScience2014FORESHORE ASSESSMENT USING SPACE TECHNOLOGY. Vegetated foreshores and floodplains provide important ecosystem services. These include benefits for coastal defence: the foreshores attenuate waves, enhance sedimentation and reduce erosion, mitigating flood risk. At present, this function of wetland ecosystems is hardly incorporated in coastal defence schemes. Yet considering foreshores and floodplains in water safety assessments and in levee design can result in considerable cost reductions for flood risk management. In the EU-funded project FAST (Foreshore Assessment using Space Technology, 2014-2018), we aim to develop a GMES/Copernicus downstream service, combining Sentinel satellite data and in situ data to integrate the functioning of wetlands in flood risk management strategies. Sentinel data will be used to retrieve relevant biophysical parameters to characterise the foreshore, such as the morphology/topography of the foreshores, the density/biomass and type of vegetation, and the sediment type. Because of their location at the dynamic interface of land and water, foreshores and floodplains pose particular challenges for satellite observation and analysis, both regarding spatial and spectral resolution (due to the large environmental gradients and heterogeneity) and regarding temporal resolution (due to the large temporal variation as a result of, for example, tidal inundation). Information on some key variables is not readily available, and applicability of some relevant biophysical parameters and indicators developed for the terrestrial realm (such as Leaf Area Index, NDVI) remain to be tested for the characterisation of foreshores. The advent of the superspectral Sentinel-2 MSI opens up the potential to detect such characteristics from a spaceborne platform in a consistent way, based on an appropriate spectral, spatial and temporal resolution, with substantial (regional) coverage. However, a thorough assessment is required to optimize and validate retrieval schemes for the spatial characterisation of foreshores. At eight case-study sites across Europe (Spain, Romania, United Kingdom and the Netherlands), ground referencing will be executed to aid the retrieval of information from Sentinel imagery. Validation includes measurements of sediment type and vegetation density/biomass and hyperspectral reflectance of vegetation types. The in situ and remote sensing data will be combined with measurements on wave attenuation and erosion/deposition regimes. The results will provide insight in forshore stability and in the buffering function of foreshores and floodplains. From the collected data general relationships between foreshore and floodplain characteristics and flood risk mitigation properties will be derived. These will be implemented in a GIS based tool for integrating wetlands into cost efficient and safe flood risk management strategies.This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration.POSTE

Development of a new methodology to try to qualitatively evaluate the physic-chemistry and socio-economical consequences due to climate change on the mouth of the Guadalquivir estuary

Trabajo presentado en el V simposio Internacional de Ciencias del Mar, celebrado en alicante del 20 al 22 de julio de 2016.Future climate projections suggest that river flow will change. This will have a sognificant impact on the downstream and estuarine enviroment. In general, recent researches have shown that a combination of increased precipitation and river flow rates in winters and decreased precipitation and river flow rates in summers.We would like to thank the regional andalusia Government (PII_RNM-7722 project) and the Spanish Government (MEGAN project CTM2013-49048-C2-2-R), and to the SUDOE INTERREG AGUAMOD project for the economic supporting of this work.N

Altimetry for the future: Building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the ‘‘Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion